Anchoring bedding slope accelerated corrosion physical model test device and method

Abstract

A physical model test device and method for accelerated corrosion of an anchored bedding slope comprises a shell, a simulated rock mass, an electrolyte system, a mechanical loading system and an observation system, a plurality of anchor rods are arranged on the front side of the simulated rock mass, a slope structure is simulated through the simulated rock mass, the simulated rock mass and the anchor rods on the simulated rock mass jointly form a simulated anchoring system, and the simulated anchoring system is connected with the electrolyte system. The electrolyte system is used for enabling electrolyte to circularly flow inside or around the simulated rock mass, and the mechanical loading system is arranged at the top of the simulated rock mass and is used for applying pressure in the vertical direction to the simulated rock mass, so that the stratified slope geologic structure, the electrochemical accelerated corrosion environment and the multi-mode mechanical load are integrally and synchronously simulated. According to the design, key elements in slope engineering can be simulated, the fidelity of a corrosion mechanism is effectively improved, the corrosion rate and an accelerated degradation mechanism of an anchor rod stress concentration area can be simulated, and the dynamic coupling process is effectively revealed.

Description

Technical Field

[0001] This invention relates to a corrosion testing device, and more particularly to a physical model testing device and method for accelerated corrosion of anchored bedding slopes. Background Technology

[0002] Layered rock slopes are widely distributed in areas where infrastructure such as mines, water conservancy, and transportation are constructed. Their stability often depends on reinforcement structures such as anchor bolts (cables). However, during long-term service, the slope anchoring system not only bears the mechanical effects of the slope's own weight, the load at the top of the slope, and tectonic stress, but also suffers from complex environmental erosion such as chemical corrosion, electrochemical corrosion, and dissolution caused by groundwater seepage. Corrosion problems are particularly prominent in sulfur-bearing strata, acidic mining areas, or near-shore environments, often leading to a reduction in the effective cross-sectional area of ​​the anchor bolts, degradation of mechanical properties, and loss of bonding strength at the anchoring interface. This can result in the gradual failure of the anchoring system or even the overall instability of the slope, seriously threatening the safety and service life of the project.

[0003] Currently, research on the performance of anchored slopes under corrosive environments often employs immersion or salt spray methods to conduct uniform corrosion tests on anchor specimens in a single medium. The immersion method involves completely immersing the anchor specimen in a prepared corrosive solution (such as NaCl solution, sulfate solution, etc.) and simulating long-term corrosion by controlling the solution concentration, pH value, and temperature. The salt spray method involves exposing the anchor specimen to a continuous or cyclically sprayed salt spray environment in a salt spray test chamber to simulate chloride ion erosion in marine atmospheres or industrially polluted areas.

[0004] Although both of these corrosion testing methods can simulate the corrosion of anchor bolts under specific environments, they still have the following drawbacks:

[0005] 1. It is impossible to simulate the localized corrosion aggravation effect caused by the non-uniform seepage of groundwater along rock fissures or pore networks in actual slopes, making it difficult to reproduce the coupling effect of electrochemical corrosion and chemical dissolution in specific geological environments, resulting in a distortion of the corrosion mechanism.

[0006] 2. When anchor bolts are under stress, the corrosion rate in stress concentration areas will be significantly accelerated. At the same time, the cross-sectional loss and interface weakening caused by corrosion will change their stress state, forming a positive feedback accelerated degradation mechanism. Existing technologies often separate corrosion tests from mechanical loading tests, first subjecting the anchor bolts to corrosion treatment for a period of time, and then conducting pull-out or shear tests, which cannot reveal the dynamic coupling process.

[0007] The information disclosed in this background section is intended only to enhance understanding of the overall background of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing technologies, such as distorted corrosion mechanisms and inability to reveal dynamic coupling processes. It provides a physical model test device and method for accelerated corrosion of anchored bedding slopes that provides a realistic corrosion mechanism and can reveal dynamic coupling processes.

[0009] To achieve the above objectives, the technical solution of the present invention is:

[0010] A physical model test device for accelerated corrosion of anchored bedding slopes, the test device comprising: a shell, a simulated rock mass, an electrolyte system, a mechanical loading system, and an observation system;

[0011] The shell is a box structure, and the simulated rock mass and mechanical loading system are both housed inside the shell;

[0012] The simulated rock mass is used to simulate the slope structure. The simulated rock mass is set on a fixed base at the bottom of the shell, and multiple anchor rods are set on the front side of the simulated rock mass.

[0013] The electrolyte system is used to circulate the electrolyte inside or around the simulated rock mass;

[0014] The mechanical loading system is installed at the top of the simulated rock mass, and the mechanical loading system is used to apply vertical pressure to the simulated rock mass;

[0015] The observation system is used to monitor the simulated rock mass and each anchor bolt in real time and collect experimental data.

[0016] The observation system includes a non-contact optical measurement device, an anchor bolt mechanical monitoring device, a rock mass internal damage monitoring device, and a deep displacement measuring instrument;

[0017] The non-contact optical measurement device consists of at least two high-definition cameras with different shooting angles, used to create a speckle field on the surface of the simulated rock mass and obtain the full-field displacement vector and strain tensor cloud map of the simulated rock mass surface during loading and corrosion.

[0018] The anchor bolt mechanical monitoring device includes multiple anchor bolt force gauges and multiple resistance strain gauges. Each anchor bolt force gauge is respectively installed between the anchor head and the gasket of an anchor bolt. The resistance strain gauges are installed on the surface of each anchor bolt. The anchor bolt force gauges are used to monitor and record the axial force change history of each anchor bolt in real time. The resistance strain gauges are used to measure the strain in local areas of the anchor bolt.

[0019] The internal damage monitoring device for the rock mass includes multiple acoustic emission sensors, which are respectively installed on the surface and inside of the simulated rock mass. The acoustic emission sensors are used to collect acoustic emission signals generated by the rock mass during stress and corrosion to monitor the development process of internal microcracks.

[0020] The deep displacement measuring instrument is a high-precision servo accelerometer-type inclinometer, used to periodically measure the horizontal displacement at different depths of the anchor hole.

[0021] The simulated rock mass includes multiple layers of parallel stacked rock slabs, which are made by mixing silicate cement, calcareous sand and deionized water in a predetermined mass ratio to simulate the physical and mechanical properties of the target rock layer.

[0022] Each layer of rock slabs is roughened at the interlayer interface or covered with an extremely thin layer of weak material;

[0023] Each of the aforementioned rock slabs has a rock stratum dip angle between it and the fixed base;

[0024] The front side of the simulated rock mass is simulated by an inclined plane to simulate a slope structure;

[0025] All of the aforementioned anchor bolts are inserted into the anchor holes on the simulated rock mass at the same angle;

[0026] Multiple anchor bolts are arranged on the simulated rock mass in a matrix, quincunx, or equivalent engineering pattern.

[0027] The mechanical loading system includes a jack and a pressure plate. The cylinder seat of the jack is in contact with the top plate of the shell. The end of the telescopic rod of the jack is in transmission cooperation with the pressure plate. The pressure plate is set on the top of the simulated rock mass.

[0028] The front side wall of the housing is provided with a liquid inlet, and the rear side wall of the housing is provided with a liquid outlet.

[0029] The electrolyte system includes a circulating pump, a working electrode, an auxiliary electrode, a reference electrode, and an electrochemical workstation. The circulating pump is used to transport the electrolyte, and the outlet of the circulating pump is connected to the inlet, while the inlet of the circulating pump is connected to the outlet.

[0030] The working electrode is connected in parallel with each anchor bolt, the auxiliary electrode is placed in the electrolyte near the front side of the simulated rock mass, and the reference electrode is placed in the electrolyte near the rear side of the simulated rock mass.

[0031] The signal input terminals of the electrochemical workstation are respectively connected to the working electrode, auxiliary electrode and reference electrode;

[0032] The electrochemical workstation is used to apply a constant anodic potential to the working electrode, monitor the potential of the working electrode relative to the reference electrode in real time, and monitor the total corrosion current flowing through the working electrode and auxiliary electrode circuit. At the same time, it performs potentiodynamic scanning or electrochemical impedance spectroscopy tests periodically.

[0033] A test method for an accelerated corrosion physical model of anchored bedding slopes, the test method comprising the following steps:

[0034] S1. Based on the structure of the slope to be tested, a simulated rock mass is manufactured. Anchor holes are drilled on the manufactured simulated rock mass, and the pre-treated anchor rods are installed into the anchor holes. The simulated rock mass with the anchor rods installed is then placed inside the shell.

[0035] S2. Connect the electrolyte system to the inlet and outlet on the shell, and install the mechanical loading system and observation system inside and outside the shell;

[0036] S3. Calibrate and initialize the electrolyte system and the observation system;

[0037] S4. The corrosion test of the anchor rod was carried out in stages under different experimental conditions using the constant potential electrochemical acceleration method, and the experimental data was collected in real time.

[0038] S5. Repeat steps S1 to S4 three times, analyze the experimental data collected three times, and obtain three sets of key parameter sequences.

[0039] S6. Multi-source information coupling is performed on the three sets of key parameter sequences to obtain failure early warning results.

[0040] In S4, the stage includes the corrosion action period, the corrosion-load coupling period, and the accelerated failure period;

[0041] The duration of the corrosion action period and the corrosion-load coupling period is 240 hours;

[0042] The experimental conditions for the corrosion period are as follows: the electrolyte system is turned on, the circulation pump starts working, and the electrolyte is circulated in the shell. At the same time, the working electrode applies a constant potential of +8.0V to each anchor rod.

[0043] During the corrosion period, the total corrosion current was recorded every 10 minutes. Through total corrosion current Calculate the corrosion current density for each anchor bolt. , This represents the total number of anchor bolts. Let be the number of any anchor bolt. The DIC data were obtained by fitting electrochemical impedance spectroscopy and by collecting all anchor stress data every 6 hours and performing full-field DIC measurement every 24 hours.

[0044] After the corrosion period lasts for 240 hours, the corrosion-load coupling period begins.

[0045] The experimental conditions for the corrosion-load coupling period are as follows: the mechanical loading system is turned on, and the jack works in a graded loading-holding mode. The initial load of the graded loading-holding mode is 50kN, the load increases by 50kN at each stage, and each stage of load is maintained for 48h.

[0046] Meanwhile, the electrolyte system remains in its operating state.

[0047] During the corrosion period, the sampling frequency of all sensors was increased to 1Hz, and the internal damage monitoring device of the rock mass continuously monitored in real time.

[0048] When the corrosion-load coupling period lasts for 240 hours, it enters the accelerated failure period;

[0049] The experimental conditions for the accelerated failure period are as follows: the mechanical loading system is switched to displacement control, and the displacement at the top of the slope is continuously increased at a rate of 2 mm / min, while the working state of the electrolyte system remains unchanged.

[0050] The experiment shall be terminated if any of the following conditions are met:

[0051] a. The stress in any anchor bolt drops to below 30% of its initial value;

[0052] b. A through crack appears on the surface of the simulated rock mass, with a width > 5 mm;

[0053] c. The deep displacement measuring instrument shows that the sliding surface displacement rate is >1 mm / min.

[0054] S5 includes preprocessing the collected experimental data;

[0055] Calculation of average corrosion depth based on Faraday's law:

[0056] ;

[0057] In the above formula, Let M be the total exposed area of ​​the 16 anchor bolts, M be the molar mass of iron (taken as 55.85 g / mol), F be the Faraday constant (taken as 96485 C / mol), and ρ be the density of iron (taken as 7.87 g / cm³). Let t be the total corrosion current density at time t, and T be the total corrosion time;

[0058] Define the corrosion non-uniformity coefficient:

[0059] ;

[0060] In the above formula, Let be the corrosion current density of the i-th anchor rod at time t. The average corrosion current density at time t is obtained by dividing the total corrosion current density at time t by the total number of anchor bolts.

[0061] Based on Kriging interpolation, spatial distribution cloud maps of corrosion current density are plotted to identify corrosion hotspots.

[0062] Surface displacement field: Extracting the displacement time histories of key points at the shoulder and toe of the slope from DIC data;

[0063] Deep displacement curve: Numerical differentiation is performed on the inclinometer data to obtain the curvature change of the displacement-depth curve;

[0064] Calculation of time t using DIC strain field Point shear strain ;

[0065] Define damage variables:

[0066] ;

[0067] In the above formula, =0.1%, which is the damage threshold. =2%, which is the damage threshold;

[0068] Draw a damage cloud map and analyze the change in the percentage of damaged area over time;

[0069] Calculate the load sharing ratio of the i-th anchor rod:

[0070] ;

[0071] In the above formula, Let be the tension of the i-th anchor rod at time t;

[0072] Construct the load distribution entropy value:

[0073] ;

[0074] In the above formula, Let be the load sharing ratio of the i-th anchor rod;

[0075] Define the effective constraint coefficient of the anchor bolt:

[0076] ;

[0077] In the above formula, The displacement of the local rock mass around the anchor bolt was extracted from DIC data. Let be the tension of the i-th anchor rod at the initial moment. This refers to the cumulative displacement of the surrounding rock mass in the local area after the slope deformation and failure.

[0078] Based on the limit equilibrium method, a safety factor model considering corrosion weakening is established:

[0079] ;

[0080] In the above formula, For safety reasons, , To take into account the strength parameters of the rock mass after dissolution, Let be the area of ​​the base of the i-th block. The anchor bolt inclination angle, The dip angle of the slip surface is measured after the simulated rock mass has slipped. The weight of the strip is the weight of the sliding portion of the simulated rock mass after it has slid.

[0081] The cumulative acoustic emission energy ΣE is obtained through a rock mass internal damage monitoring device, and the deep displacement rate is obtained through a deep displacement measuring instrument. Slope shoulder displacement is obtained through a non-contact optical measurement device. ;

[0082] The cumulative acoustic emission energy ΣE and deep displacement rate from the three experiments were used to calculate the cumulative acoustic emission energy ΣE and the deep displacement rate. Slope shoulder displacement With total corrosion current Corrosion non-uniformity coefficient Average corrosion depth Load distribution entropy value Safety factor They are packaged into three key parameter sequences.

[0083] The steps for multi-source information coupling are as follows:

[0084] For each key parameter sequence, different key parameters in the key parameter sequence are paired to form parameter pairs. The correlation coefficient is obtained by calculating the relationship between each parameter pair using a sliding window cross-correlation function.

[0085] The parameter pairs corresponding to the correlation coefficients that are greater than the set threshold are taken as causal parameter pairs, and the causal parameter pairs are packaged to obtain a set of causal relationships.

[0086] Repeatable causal parameter pairs are identified in three sets of causal relationships. Causal analysis is performed on the causal parameter pairs, and the cause parameters in the causal parameter pairs are used as precursor features. The warning index is calculated through the precursor features, and the calculated warning index is compared with the warning threshold to obtain the warning level.

[0087] In step S6, the sliding window cross-correlation function is calculated using a sequence of key parameters. The sliding window has a width of 48 hours and a step size of 1 hour. This includes:

[0088] ;

[0089] In the above formula, X is the correlation coefficient, and X and Y are two key parameters in the parameter pair.

[0090] In S6, the early warning index includes:

[0091] ;

[0092] In the above formula, For the first A few early warning features Normalized data at any given time This represents the total number of precursory features. For the first The weights corresponding to each precursor feature;

[0093] When 0.3≤ When the value is less than 0.5, it is a Level I warning, and no signal is issued.

[0094] When 0.5≤ When the value is less than 0.7, it is a Level II warning, and a warning signal will be issued.

[0095] when When the value is ≥0.7, it is a Level III warning, and an alarm signal is issued.

[0096] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0097] 1. In the physical model test device for accelerated corrosion of bedding slopes, multiple anchor rods are installed on the front side of the simulated rock mass. The simulated rock mass simulates the slope structure, and the simulated rock mass and the anchor rods together form a simulated anchoring system. An electrolyte system is used to circulate the electrolyte inside or around the simulated rock mass. A mechanical loading system is set on the top of the simulated rock mass to apply vertical pressure, thereby achieving integrated and synchronized simulation of the geological structure of bedding slopes, the electrochemical accelerated corrosion environment, and multi-mode mechanical loads. Therefore, this design can simulate key elements in slope engineering and effectively improve the realism of the corrosion mechanism.

[0098] 2. In the physical model test device for accelerated corrosion of anchored bedding slopes of this invention, multiple anchors are arranged in a matrix, quincunx, or equivalent engineering pattern on the simulated rock mass. This allows for the study of the anchors as a group, revealing the complex relationship between individual anchor performance degradation and group functional succession under corrosion and load. By monitoring the response of each anchor, load redistribution, failure propagation paths, and the redundancy and vulnerability of the system can be analyzed. Therefore, this design can study the corrosion mechanism of anchor group systems under corrosion and load, effectively improving experimental results.

[0099] 3. In the experimental method of the physical model for accelerated corrosion of anchored bedding slopes of this invention, a constant potential electrochemical acceleration method is used to conduct corrosion experiments on anchors in stages under different experimental conditions, while simultaneously collecting experimental data in real time. This can simulate the corrosion rate and accelerated degradation mechanism of anchors under stress in actual use environments. Therefore, this design can simulate the corrosion rate and accelerated degradation mechanism of anchor stress concentration areas, effectively revealing the dynamic coupling process.

[0100] The corrosion acceleration method is scientifically sound and controllable: The constant potential electrochemical acceleration method employed can directionally and quantitatively accelerate the electrochemical corrosion process of anchor bolts without introducing external conditions such as high temperatures or ultra-high concentrations that may alter the corrosion mechanism. Combined with real-time electrochemical monitoring, it not only shortens the experimental cycle but also obtains continuous corrosion kinetic data, providing a solid foundation for establishing a corrosion rate prediction model. Attached Figure Description

[0101] Figure 1 This is a schematic diagram of the structure of the device described in this invention.

[0102] Figure 2 This is a side view of the device described in this invention.

[0103] Figure 3 This is a flowchart of the method described in this invention.

[0104] Figure 4 This is a block diagram of the electrochemical accelerated corrosion and monitoring system in Example 1.

[0105] Figure 5 This is a flowchart of the multi-stage accelerated corrosion test and monitoring process in Example 2.

[0106] Figure 6 This is a flowchart of multi-source information coupling and early warning analysis.

[0107] Figure 7 This is a schematic diagram illustrating the calculation and significance of load distribution entropy.

[0108] In the diagram: 1. Shell 1, 2. Fixed base 11, 3. Liquid inlet 12, 4. Liquid outlet 13, 5. Simulated rock mass 2, 6. Front side 21, 7. Rock plate 22, 8. Electrolyte system 3, 9. Circulating pump 31, 10. Working electrode 32, 11. Auxiliary electrode 33, 12. Reference electrode 34, 13. Electrochemical workstation 35, 14. Mechanical loading system 4, 15. Jack 41, 16. Pressure plate 42, 17. Observation system 5, 18. Non-contact optical measurement device 51, 19. Anchor bolt mechanical monitoring device 52, 10. Rock mass internal damage monitoring device 53, 11. Deep displacement measuring instrument 54, 12. Anchor bolt 6. Detailed Implementation

[0109] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0110] Example 1:

[0111] See Figure 1 and Figure 2 A physical model test device for accelerated corrosion of anchored bedding slopes, characterized in that...

[0112] The experimental apparatus includes: a shell 1, a simulated rock mass 2, an electrolyte system 3, a mechanical loading system 4, and an observation system 5. The shell 1 is a box structure, and the simulated rock mass 2 and the mechanical loading system 4 are both housed within the shell 1. The simulated rock mass 2 is used to simulate a slope structure and is mounted on a fixed base 11 at the bottom of the shell 1. Multiple anchor rods 6 are mounted on the front side 21 of the simulated rock mass 2. The electrolyte system 3 is used to circulate the electrolyte inside or around the simulated rock mass 2. The mechanical loading system 4 is located at the top of the simulated rock mass 2 and is used to apply vertical pressure to the simulated rock mass 2. The observation system 5 is used to monitor the simulated rock mass 2 and each anchor rod 6 in real time and collect experimental data.

[0113] By elevating the research perspective from individual units to the entire system, and studying anchor bolt 6 as a group, we can reveal the complex relationship between the individual performance degradation of anchor bolt 6 and the functional succession of the group under corrosion and load. By monitoring the response of each anchor bolt 6, we can analyze the load redistribution, the failure transmission path, and the redundancy and vulnerability of the system. This is a breakthrough that cannot be achieved by single anchor bolt tests.

[0114] The observation system 5 includes a non-contact optical measurement device 51, an anchor bolt mechanical monitoring device 52, a rock mass internal damage monitoring device 53, and a deep displacement measuring instrument 54.

[0115] The non-contact optical measurement device 51 consists of at least two high-definition cameras with different shooting angles, used to create a speckle field on the surface of the simulated rock mass 2, and obtain the full-field displacement vector and strain tensor cloud map of the surface of the simulated rock mass 2 during the loading and corrosion process.

[0116] The anchor bolt mechanical monitoring device 52 includes multiple anchor bolt force gauges and multiple resistance strain gauges. Each anchor bolt force gauge is respectively set between the anchor head and the gasket of an anchor bolt 6. The resistance strain gauges are set on the surface of each anchor bolt. The anchor bolt force gauges are used to monitor and record the axial force change history of each anchor bolt in real time. The resistance strain gauges are used to measure the strain in the local area of ​​the anchor bolt.

[0117] The internal damage monitoring device 53 of the rock mass includes multiple acoustic emission sensors, which are respectively set on the surface and inside of the simulated rock mass 2. The acoustic emission sensors are used to collect acoustic emission signals generated by the rock mass during stress and corrosion to monitor the development process of internal microcracks.

[0118] The deep displacement measuring instrument 54 is a high-precision servo accelerometer-type inclinometer, used to periodically measure the horizontal displacement at different depths of the anchor hole.

[0119] The simulated rock mass 2 includes multiple layers of parallel stacked rock slabs 22, which are made by mixing silicate cement, calcareous sand, and deionized water in a predetermined mass ratio to simulate the physical and mechanical properties of the target rock strata. Each layer of rock slabs 22 is roughened at the interlayer interface or laid with an extremely thin layer of weak material. Each layer of rock slabs 22 has a rock strata dip angle with the fixed base 11. The front side 21 of the simulated rock mass 2 is simulated by a slope structure. Multiple anchor rods 6 are inserted into anchor holes on the simulated rock mass 2 at the same angle. Multiple anchor rods 6 are arranged on the simulated rock mass 2 in a matrix, quincunx, or engineering equivalent pattern. The mechanical loading system 4 includes a jack 41 and a pressure plate 42. The cylinder seat of the jack 41 is in contact with the top plate of the shell 1. The end of the telescopic rod of the jack 41 is in transmission cooperation with the pressure plate 42. The pressure plate 42 is set on the top of the simulated rock mass 2.

[0120] Using similarity theory-based materials, the main components of simulated rock mass 2 include ordinary silicate cement, calcareous sand with specific gradation, and deionized water. By precisely controlling the proportion of each component (e.g., cement:calcareous sand:water = 1:3:0.4), a series of mechanical and permeability properties from soft and weak strongly weathered rock layers to hard and intact rock layers can be simulated.

[0121] At the same time, by adopting different anchoring schemes, the material, diameter, length, spacing, inclination angle and arrangement of the anchor rods can be flexibly changed to optimize the anchoring design.

[0122] The front side wall of the housing 1 is provided with a liquid inlet 12, and the rear side wall of the housing 1 is provided with a liquid outlet 13;

[0123] See Figure 3The electrolyte system 3 includes a circulating pump 31, a working electrode 32, an auxiliary electrode 33, a reference electrode 34, and an electrochemical workstation 35. The circulating pump 31 is used to transport the electrolyte, and its outlet end is connected to the inlet 12, while its inlet end is connected to the outlet 13. The working electrode 32 is connected in parallel with each anchor rod 6. The auxiliary electrode 33 is placed in the electrolyte near the front side 21 of the simulated rock mass 2, and the reference electrode 34 is placed in the electrolyte near the rear side of the simulated rock mass 2. The signal input terminal of the electrochemical workstation 35 is connected to the working electrode 32, the auxiliary electrode 33, and the reference electrode 34, respectively. The electrochemical workstation 35 is used to apply a constant anodic potential to the working electrode 32, monitor the potential of the working electrode 32 relative to the reference electrode 34 in real time, monitor the total corrosion current flowing through the circuit of the working electrode 32 and the auxiliary electrode 33, and periodically perform potentiodynamic scanning or electrochemical impedance spectroscopy tests.

[0124] By changing the electrolyte composition, various corrosive environments such as acidic mine water, seawater, and saline soil can be simulated.

[0125] Example 2:

[0126] See Figure 4 and Figure 5 A test method for an accelerated corrosion physical model of anchored bedding slopes, the test method comprising the following steps:

[0127] S1. Based on the structure of the slope to be tested, a simulated rock mass 2 is manufactured. Anchor holes are drilled on the manufactured simulated rock mass 2, and the pre-treated anchor rods 6 are installed into the anchor holes. The simulated rock mass 2 with the anchor rods 6 installed is placed inside the shell 1.

[0128] S2. Connect the electrolyte system 3 to the inlet 12 and outlet 13 on the housing 1, and install the mechanical loading system 4 and the observation system 5 inside and outside the housing 1.

[0129] S3. Calibrate and initialize the electrolyte system 3 and the observation system 5;

[0130] S4. The corrosion test of anchor rod 6 was carried out in stages under different experimental conditions using the constant potential electrochemical acceleration method, and the experimental data was collected in real time.

[0131] S5. Repeat steps S1 to S4 three times, analyze the experimental data collected three times, and obtain three sets of key parameter sequences.

[0132] S6. Multi-source information coupling is performed on the three sets of key parameter sequences to obtain failure early warning results.

[0133] In S4, the stage includes the corrosion action period, the corrosion-load coupling period, and the accelerated failure period;

[0134] The duration of the corrosion action period and the corrosion-load coupling period is 240 hours;

[0135] The experimental conditions for the corrosion period are as follows: the electrolyte system 3 is turned on, the circulation pump 31 starts to work, and the electrolyte is circulated in the shell 1. At the same time, the working electrode 32 applies a constant potential of +8.0V to each anchor rod 6.

[0136] During the corrosion period, the total corrosion current was recorded every 10 minutes. Through total corrosion current Calculate the corrosion current density for each anchor bolt 6. , For the total number of anchor bolts 6, Let 6 be the number of any anchor bolt. The DIC data were obtained by fitting electrochemical impedance spectroscopy and by collecting stress data of all anchor bolts every 6 hours and performing full-field DIC measurement every 24 hours.

[0137] After the corrosion period lasts for 240 hours, the corrosion-load coupling period begins.

[0138] The experimental conditions for the corrosion-load coupling period are as follows: the mechanical loading system 4 is turned on, and the jack 41 works in the graded loading-holding mode. The initial load of the graded loading-holding mode is 50kN, and the load increases by 50kN for each grade. Each load is maintained for 48h.

[0139] Meanwhile, the working state of the electrolyte system 3 remains unchanged;

[0140] During the corrosion period, the sampling frequency of all sensors was increased to 1Hz, and the internal damage monitoring device 53 of the rock mass continuously monitored in real time.

[0141] When the corrosion-load coupling period lasts for 240 hours, it enters the accelerated failure period;

[0142] The experimental conditions for the accelerated failure period are as follows: the mechanical loading system 4 is switched to displacement control, and the displacement at the top of the slope is continuously increased at a rate of 2 mm / min, while the working state of the electrolyte system 3 remains unchanged.

[0143] The experiment shall be terminated if any of the following conditions are met:

[0144] a. The stress in any anchor bolt 6 drops to below 30% of its initial value;

[0145] b. A through crack with a width > 5 mm appears on the surface of simulated rock mass 2;

[0146] c. The deep displacement measuring instrument 54 shows that the sliding surface displacement rate is >1 mm / min.

[0147] S5 includes preprocessing the collected experimental data;

[0148] The data preprocessing process includes raw data, time-scale alignment (PTP protocol), outlier detection (3σ criterion), missing value handling (cubic spline interpolation), noise reduction (wavelet transform, db4 wavelet, 5-level decomposition), normalization, and standardized database.

[0149] Calculation of average corrosion depth based on Faraday's law:

[0150] ;

[0151] In the above formula, Let M be the total exposed area of ​​the 16 anchor bolts, M be the molar mass of iron (taken as 55.85 g / mol), F be the Faraday constant (taken as 96485 C / mol), and ρ be the density of iron (taken as 7.87 g / cm³). Let t be the total corrosion current density at time t, and T be the total corrosion time;

[0152] Define the corrosion non-uniformity coefficient:

[0153] ;

[0154] In the above formula, Let be the corrosion current density of the i-th anchor rod at time t. The average corrosion current density at time t is obtained by dividing the total corrosion current density at time t by the total number of anchor bolts 6.

[0155] Based on Kriging interpolation, spatial distribution cloud maps of corrosion current density are plotted to identify corrosion hotspots.

[0156] The corrosion hotspot areas are used to evaluate the spatial distribution of anchor bolt corrosion.

[0157] Surface displacement field: Extracting the displacement time histories of key points at the shoulder and toe of the slope from DIC data;

[0158] Deep displacement curve: Numerical differentiation is performed on the inclinometer data to obtain the curvature change of the displacement-depth curve;

[0159] The deep displacement curve is used to analyze and obtain the internal displacement field of the slope.

[0160] Calculation of time t using DIC strain field Point shear strain ;

[0161] Define damage variables:

[0162] ;

[0163] In the above formula, =0.1%, which is the damage threshold. =2%, which is the damage threshold;

[0164] Draw a damage cloud map and analyze the change in the percentage of damaged area over time;

[0165] The damage cloud map is used to analyze and assess the local damage to the slope.

[0166] Calculate the load sharing ratio of the i-th anchor rod:

[0167] ;

[0168] In the above formula, Let be the tension of the i-th anchor rod 6 at time t;

[0169] Construct the load distribution entropy value:

[0170] ;

[0171] In the above formula, Let be the load sharing ratio of the i-th anchor rod;

[0172] Define the effective constraint coefficient of the anchor bolt:

[0173] ;

[0174] In the above formula, The displacement of the local rock mass around the anchor bolt was extracted from DIC data. Let be the tension of the i-th anchor rod at the initial moment. This refers to the cumulative displacement of the surrounding rock mass in the local area after the slope deformation and failure.

[0175] Based on the limit equilibrium method, a safety factor model considering corrosion weakening is established:

[0176] ;

[0177] In the above formula, For safety reasons, , To take into account the strength parameters of the rock mass after dissolution, Let be the area of ​​the base of the i-th block. The anchor bolt inclination angle, The dip angle of the slip surface is measured after the simulated rock mass 2 has slipped. The weight of the strip is the weight of the sliding portion of the simulated rock mass 2 after it slides.

[0178] The cumulative acoustic emission energy ΣE is obtained through the internal rock mass damage monitoring device 53, and the deep displacement rate is obtained through the deep displacement measuring instrument 54. The slope shoulder displacement is obtained through a non-contact optical measurement device 51. ;

[0179] The cumulative acoustic emission energy ΣE and deep displacement rate from the three experiments were used to calculate the cumulative acoustic emission energy ΣE and the deep displacement rate. Slope shoulder displacement With total corrosion current Corrosion non-uniformity coefficient Average corrosion depth Load distribution entropy value Safety factor They are packaged into three key parameter sequences.

[0180] The steps for multi-source information coupling are as follows:

[0181] For each key parameter sequence, different key parameters in the key parameter sequence are paired to form parameter pairs. The correlation coefficient is obtained by calculating the relationship between each parameter pair using a sliding window cross-correlation function.

[0182] The parameter pairs corresponding to the correlation coefficients that are greater than the set threshold are taken as causal parameter pairs, and the causal parameter pairs are packaged to obtain a set of causal relationships.

[0183] Repeatable causal parameter pairs are identified in three sets of causal relationships. Causal analysis is performed on the causal parameter pairs, and the cause parameters in the causal parameter pairs are used as precursor features. The warning index is calculated through the precursor features, and the calculated warning index is compared with the warning threshold to obtain the warning level.

[0184] In step S6, the sliding window cross-correlation function is calculated using a sequence of key parameters. The sliding window has a width of 48 hours and a step size of 1 hour. This includes:

[0185] ;

[0186] In the above formula, X and Y are the correlation coefficients, and X and Y are the two key parameters in the parameter pair.

[0187] The set threshold is 0.7. When |ρ|>0.7 and τ>0, it is considered that X leads the change of Y, and X is the cause parameter.

[0188] The relationship between changes in X and Y is used to reveal the causal relationship and chain of action in the process of system failure. X leading the change in Y means that, at the physical level, the process represented by X (such as increased corrosion and accumulation of micro-damage) is the driving factor or precursor to the consequences represented by Y (such as decreased load-bearing capacity and macroscopic deformation). It helps us to sort out a clear time sequence of "cause and effect" from complex phenomena that occur at the same time.

[0189] From an engineering application perspective, this discovery can identify key sentinel indicators. For example, if abnormal fluctuations in corrosion current consistently precede the acceleration of slope displacement, then monitoring corrosion current can provide a valuable early warning window before significant slope instability occurs. This directly guides us on which parameters should be prioritized for monitoring to prevent disasters.

[0190] Furthermore, this lead-lag relationship provides a crucial constraint for constructing and validating numerical models; a theoretical model capable of accurately simulating reality must be able to reproduce this observed time lag. This significantly improves the reliability of lifetime prediction and risk analysis.

[0191] In summary, this analysis elevates monitoring data from a simple "phenomenon record" to a "clue map" for understanding system failure mechanisms, making data-driven early warning and precise intervention possible. This is the core value of the experimental device constructed in this patent.

[0192] pass Create a cause-and-effect diagram.

[0193] See Figure 6 In step S6, the early warning index includes:

[0194] ;

[0195] In the above formula, For the first A few early warning features Normalized data at any given time This represents the total number of precursory features. For the first The weights corresponding to each precursor feature;

[0196] When 0.3≤ When the value is less than 0.5, it is a Level I warning, and no signal is issued.

[0197] When 0.5≤ When the value is less than 0.7, it is a Level II warning, and a warning signal will be issued.

[0198] when When the value is ≥0.7, it is a Level III warning, and an alarm signal is issued.

[0199] Example 3:

[0200] Example 3 is basically the same as Example 2, except that:

[0201] See Figure 7 Total number of anchor bolts 6 For 16, the conductive areas at the upper ends of all 16 anchor rods 6 are connected in parallel by 16 mm² multi-strand copper core cables, connected to the main junction box, and then connected to the working electrode port of the electrochemical workstation 35 to form a network of working electrodes 32.

[0202] Four 300 mm × 300 mm × 10 mm graphite plates are arranged at the four corners of the shell 1, 100 mm away from the surface of the simulated rock mass 2. They are connected to the auxiliary electrode port of the workstation through titanium wire to form auxiliary electrode 33.

[0203] Two saturated calomel electrodes (SCE) were used and brought close to the key anchor rods 6 at the top and bottom of the simulated rock mass 2 through Lugin capillaries (1 mm tip diameter). The capillaries were filled with saturated KCl agar salt bridges to form reference electrodes 34.

[0204] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A physical model test device for accelerated corrosion of anchored bedding slopes, characterized in that, The experimental device includes: a shell (1), a simulated rock mass (2), an electrolyte system (3), a mechanical loading system (4), and an observation system (5); The shell (1) is a square box structure, and the simulated rock mass (2) and the mechanical loading system (4) are both set inside the shell (1); The simulated rock mass (2) is used to simulate the slope structure. The simulated rock mass (2) is set on the fixed base (11) at the bottom of the shell (1). Multiple anchor rods (6) are set on the front side (21) of the simulated rock mass (2). The electrolyte system (3) is used to circulate the electrolyte inside or around the simulated rock mass (2); The mechanical loading system (4) is set on the top of the simulated rock mass (2), and the mechanical loading system (4) is used to apply vertical pressure to the simulated rock mass (2); The observation system (5) is used to monitor the simulated rock mass (2) and each anchor rod (6) in real time and collect experimental data.

2. The physical model test device for accelerated corrosion of anchored bedding slopes according to claim 1, characterized in that, The observation system (5) includes a non-contact optical measurement device (51), an anchor bolt mechanical monitoring device (52), a rock mass internal damage monitoring device (53), and a deep displacement measuring instrument (54). The non-contact optical measurement device (51) consists of at least two high-definition cameras with different shooting angles, used to create a speckle field on the surface of the simulated rock mass (2) and obtain the full-field displacement vector and strain tensor cloud map of the surface of the simulated rock mass (2) during loading and corrosion. The anchor bolt mechanical monitoring device (52) includes multiple anchor bolt force gauges and multiple resistance strain gauges. Each anchor bolt force gauge is respectively set between the anchor head and the gasket of an anchor bolt (6). The resistance strain gauges are set on the surface of each anchor bolt. The anchor bolt force gauges are used to monitor and record the axial force change history of each anchor bolt in real time. The resistance strain gauges are used to measure the strain in the local area of ​​the anchor bolt. The internal damage monitoring device (53) of the rock mass includes multiple acoustic emission sensors, which are respectively set on the surface and inside of the simulated rock mass (2). The acoustic emission sensors are used to collect acoustic emission signals generated by the rock mass during stress and corrosion to monitor the development process of internal microcracks. The deep displacement measuring instrument (54) is a high-precision servo accelerometer inclinometer used to periodically measure the horizontal displacement at different depths of the anchor hole.

3. The physical model test device for accelerated corrosion of anchored bedding slopes according to claim 1, characterized in that, The simulated rock mass (2) includes multiple parallel stacked rock slabs (22), which are made by mixing silicate cement, calcareous sand and deionized water in a predetermined mass ratio to simulate the physical and mechanical properties of the target rock layer. The rock slabs (22) in each layer are roughened at the interlayer interface or laid with a very thin layer of weak material; Each of the rock slabs (22) has a rock layer dip angle with the fixed base (11); The front side (21) of the simulated rock mass (2) is simulated by a slope structure; Multiple anchor rods (6) are inserted into the anchor holes on the simulated rock mass (2) at the same angle; Multiple anchor bolts (6) are arranged on the simulated rock mass (2) in a matrix, quincunx, or engineering equivalent pattern; The mechanical loading system (4) includes a jack (41) and a pressure plate (42). The cylinder seat of the jack (41) is in contact with the top plate of the shell (1). The end of the telescopic rod of the jack (41) is in transmission cooperation with the pressure plate (42). The pressure plate (42) is set on the top of the simulated rock mass (2).

4. The physical model test device for accelerated corrosion of anchored bedding slopes according to claim 1, characterized in that, The front side wall of the housing (1) is provided with a liquid inlet (12), and the rear side wall of the housing (1) is provided with a liquid outlet (13). The electrolyte system (3) includes a circulating pump (31), a working electrode (32), an auxiliary electrode (33), a reference electrode (34), and an electrochemical workstation (35). The circulating pump (31) is used to transport the electrolyte. The outlet of the circulating pump (31) is connected to the inlet (12), and the inlet of the circulating pump (31) is connected to the outlet (13). The working electrode (32) is connected in parallel with each anchor rod (6), the auxiliary electrode (33) is placed in the electrolyte near the front side (21) of the simulated rock mass (2), and the reference electrode (34) is placed in the electrolyte near the rear side of the simulated rock mass (2). The signal input terminals of the electrochemical workstation (35) are respectively connected to the working electrode (32), the auxiliary electrode (33) and the reference electrode (34); The electrochemical workstation (35) is used to apply a constant anodic potential to the working electrode (32), monitor the potential of the working electrode (32) relative to the reference electrode (34) in real time, monitor the total corrosion current flowing through the circuit of the working electrode (32) and the auxiliary electrode (33), and perform potentiodynamic scanning or electrochemical impedance spectroscopy tests periodically.

5. A test method for the physical model of accelerated corrosion of anchored bedding slopes as described in any one of claims 1 to 4, characterized in that, The experimental method includes the following steps: S1. Based on the structure of the slope to be tested, a simulated rock mass (2) is manufactured. Anchor holes are drilled on the manufactured simulated rock mass (2), and the pre-treated anchor rods (6) are installed in the anchor holes. The simulated rock mass (2) with the anchor rods (6) installed is placed inside the shell (1). S2. Connect the electrolyte system (3) to the inlet (12) and outlet (13) on the shell (1), and install the mechanical loading system (4) and the observation system (5) inside and outside the shell (1); S3. Calibrate and initialize the electrolyte system (3) and the observation system (5); S4. The corrosion test of the anchor rod (6) was carried out in stages under different experimental conditions using the constant potential electrochemical acceleration method, and the experimental data were collected in real time. S5. Repeat steps S1 to S4 three times, analyze the experimental data collected three times, and obtain three sets of key parameter sequences. S6. Multi-source information coupling is performed on the three sets of key parameter sequences to obtain failure early warning results.

6. The test method for an accelerated corrosion physical model of an anchored bedding slope according to claim 5, characterized in that, In S4, the stage includes the corrosion action period, the corrosion-load coupling period, and the accelerated failure period; The duration of the corrosion action period and the corrosion-load coupling period is 240 hours; The experimental conditions for the corrosion period are as follows: the electrolyte system (3) is turned on, the circulation pump (31) starts to work, and the electrolyte is circulated in the shell (1). At the same time, the working electrode (32) applies a constant potential of +8.0V to each anchor rod (6). During the corrosion period, the total corrosion current was recorded every 10 minutes. Through total corrosion current Calculate the corrosion current density of each anchor rod (6). , For the total number of anchor bolts (6), Let the number of any anchor rod (6) be , The data were obtained by fitting electrochemical impedance spectroscopy and by collecting stress data of all anchor rods (6) every (6) hours and performing DIC full-field measurement every 24 hours. After the corrosion period lasts for 240 hours, the corrosion-load coupling period begins. The experimental conditions for the corrosion-load coupling period are as follows: the mechanical loading system (4) is turned on, and the jack (41) works in the graded loading-holding mode. The initial load of the graded loading-holding mode is 50kN, and the load increases by 50kN for each grade. Each load is maintained for 48h. Meanwhile, the working state of the electrolyte system (3) remains unchanged; During the corrosion period, the sampling frequency of all sensors was increased to 1Hz, and the internal damage monitoring device (53) continuously monitored the damage in the rock mass in real time. When the corrosion-load coupling period lasts for 240 hours, it enters the accelerated failure period; The experimental conditions for the accelerated failure period are as follows: the mechanical loading system (4) is switched to displacement control and the slope top displacement is continuously increased at a rate of (2) mm / min, while the working state of the electrolyte system (3) remains unchanged. The experiment will be terminated if any of the following conditions are met: a. The stress of any anchor bolt (6) drops to below 30% of its initial value; b. The simulated rock mass (2) has through cracks on its surface with a width >5mm; c. The deep displacement measuring instrument (54) shows that the sliding surface displacement rate is >1 mm / min.

7. The test method for an accelerated corrosion physical model of an anchored bedding slope according to claim 5, characterized in that, S5 includes preprocessing the collected experimental data; Calculation of average corrosion depth based on Faraday's law: ； In the above formula, Let M be the total exposed area of ​​the 16 anchor bolts, M be the molar mass of iron (taken as 55.85 g / mol), F be the Faraday constant (taken as 96485 C / mol), and ρ be the density of iron (taken as 7.87 g / cm³). Let t be the total corrosion current density at time t, and T be the total corrosion time; Define the corrosion non-uniformity coefficient: ； In the above formula, Let be the corrosion current density of the i-th anchor rod (6) at time t. The average corrosion current density at time t is obtained by dividing the total corrosion current density at time t by the total number of anchor bolts (6); Based on Kriging interpolation, spatial distribution cloud maps of corrosion current density are plotted to identify corrosion hotspots. Surface displacement field: Extracting the displacement time histories of key points at the shoulder and toe of the slope from DIC data; Deep displacement curve: Numerical differentiation is performed on the inclinometer data to obtain the curvature change of the displacement-depth curve; Calculation of time t using DIC strain field Point shear strain ; Define damage variables: ； In the above formula, =0.1%, which is the damage threshold. =2%, which is the damage threshold; Draw a damage cloud map and analyze the change in the percentage of damaged area over time; Calculate the load sharing ratio of the i-th anchor rod: ； In the above formula, Let be the tension of the i-th anchor rod (6) at time t; Construct the load distribution entropy value: ； In the above formula, Let be the load sharing ratio of the i-th anchor rod; Define the effective constraint coefficient of the anchor bolt: ； In the above formula, The displacement of the local rock mass around the anchor bolt was extracted from DIC data. Let be the tension of the i-th anchor rod at the initial moment. This refers to the cumulative displacement of the surrounding rock mass in the local area after the slope deformation and failure. Based on the limit equilibrium method, a safety factor model considering corrosion weakening is established: ； In the above formula, For safety reasons, , To take into account the strength parameters of the rock mass after dissolution, Let be the area of ​​the base of the i-th block. The anchor bolt inclination angle, The dip angle of the sliding surface is measured after the simulated rock mass (2) has slid. The weight of the strip, the weight of the strip The weight of the sliding portion of the simulated rock mass (2) after it slides is calculated. The cumulative acoustic emission energy ΣE is obtained by the internal rock mass damage monitoring device (53), and the deep displacement rate is obtained by the deep displacement measuring instrument (54). The slope shoulder displacement is obtained by a non-contact optical measurement device (51). ; The cumulative acoustic emission energy ΣE and deep displacement rate from the three experiments were used to calculate the cumulative acoustic emission energy ΣE and the deep displacement rate. Slope shoulder displacement With total corrosion current Corrosion non-uniformity coefficient Average corrosion depth Load distribution entropy value Safety factor They are packaged into three key parameter sequences.

8. The test method for an accelerated corrosion physical model of an anchored bedding slope according to claim 5, characterized in that, The steps for multi-source information coupling are as follows: For each key parameter sequence, different key parameters in the key parameter sequence are paired to form parameter pairs. The correlation coefficient is obtained by calculating the relationship between each parameter pair using a sliding window cross-correlation function. The parameter pairs corresponding to the correlation coefficients that are greater than the set threshold are taken as causal parameter pairs, and the causal parameter pairs are packaged to obtain a set of causal relationships. Repeatable causal parameter pairs are identified in three sets of causal relationships. Causal analysis is performed on the causal parameter pairs, and the cause parameters in the causal parameter pairs are used as precursor features. The warning index is calculated through the precursor features, and the calculated warning index is compared with the warning threshold to obtain the warning level.

9. The test method for an accelerated corrosion physical model of an anchored bedding slope according to claim 8, characterized in that, In step S6, the sliding window cross-correlation function is calculated using a sequence of key parameters. The sliding window has a width of 48 hours and a step size of 1 hour. This includes: ； In the above formula, X is the correlation coefficient, and X and Y are two key parameters in the parameter pair.

10. The test method for an accelerated corrosion physical model of an anchored bedding slope according to claim 8, characterized in that, In S6, the early warning index includes: ； In the above formula, For the first A few early warning features Normalized data at any given time This represents the total number of precursory features. For the first The weights corresponding to each precursor feature; When 0.3≤ When the value is less than 0.5, it is a Level I warning, and no signal is issued. When 0.5≤ When the value is less than 0.7, it is a Level II warning, and a warning signal will be issued. when When the value is ≥0.7, it is a Level III warning, and an alarm signal is issued.

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